1. Field of the Invention
The present invention relates, in general, to an arc fault detection apparatus and, more particularly, to an arc fault detection apparatus using a microcomputer, which divides current paths into a low current path and a high current path depending on the intensity of load current using a source voltage that is applied to a lead wire and determines whether an arc fault signal exists, and which presets a circuit breaking time against the generation of an arc, corresponding to the magnitude of a load, and immediately breaks a circuit if a corresponding arc fault signal is detected within the preset circuit breaking time.
2. Description of the Related Art
As well known to those skilled in the art, arc faults (series, parallel or ground arcs) occur along electric wiring, and are phenomena occurring due to physical or electric defects caused by the aging or breakdown of wires, defective insulation or overcurrent. Such an arc fault is a major factor in causing fires, so that, recently, a circuit breaker for arc fault protection to break a power supply circuit when an arc occurs on an electrical appliance must be mandatorily used in the U.S.A.
As prior arts related to such an arc fault detector, there are Korean Pat. Appln. Nos. 10-2004-59272 and 10-2004-62043.
The prior arts disclose arc fault detection apparatuses, which detect a source voltage applied to a lead wire and determine whether an arc fault has occurred, thus eliminating malfunction caused by a current detection scheme that is the technology previous to the prior arts, which divide current paths into two paths depending on the intensity of load current generated from the lead wire and determine whether an arc fault occurs based on voltage detection, thus preventing malfunction caused by a pseudo arc signal, and which shorten a circuit breaking time according to the magnitude of a load, thus greatly decreasing risk of causing fires.
Therefore, with the development of the prior arts, advanced technology has been provided to easily detect an arc generated at a load current below a rated current, as well as a load current above the rated current, so as to promptly break a circuit, and, in addition, to eliminate a malfunction of misconceiving a pseudo arc signal, generated due to the construction of various (a plurality of) loads, as an actual arc signal and erroneously breaking a circuit.
However, in the prior arts, the core technology is a method of storing a detection signal, which oscillates in and is input from an analog circuit, in a capacitor, comparing the stored signal with a preset reference signal, and outputting comparison results when current paths are divided into a low current path and a high current path according to the magnitude of a load and it is determined whether an arc fault signal exists. Therefore, output time is not uniform because of the discharging time of the capacitor, so that there may occur several malfunctions in such a way that an arc cutoff time (the period ranging from the generation of an arc to the breaking of a circuit) is not exact.